1. Field of the Invention
The present invention relates to an air cushion, and more particularly to a one-pieced air cushion that is semi-spherical and easily produced.
2. Description of Related Art
Many devices are known for facilitating exercises done for therapy, conditioning or physical training. Other than variable resistance training equipment, these devices have not usually offered much adjustability to allow for exercises at different degrees of difficulty. Also, many of these devices have been dedicated to very specific exercises and therefore do not justify a significant investment of space and financial resources for such a narrow purpose.
Some exercise devices require a person to maintain balance and equilibrium. A large inflatable ball, know as a Swiss ball, has been used for this purpose. While the ball is useful for certain stability training exercises, standing upon the ball or swaying atop the ball require a high degree of skill and is inappropriate for most.
Therefore, a conventional air cushion is shaped partially spherical (most are semi-spherical) and is invented to substitute the inflatable ball to provide a mild and easy training way to users. With reference to FIG. 7, the conventional inflatable device is composed of a base (50), a bladder (60) and a securing frame (70).
The base (50) is a round plate and has a top face (52), a bottom face (not numbered), and a clamping edge (54) around the round plate. The bladder (60) is semi-spherical shaped and has an inflatable top (62), a flat bottom side (not shown), a clamping rim (66) formed at joint of the inflatable top (62) and the flat bottom side. The bladder (60) is mounted on the top face (52) of the base (50) to which the flat bottom side (64) of the bladder (60) is attached, wherein the clamping edge (54) of the base (50) overlaps with the clamping rim (66) of the bladder (60).
The securing frame (70) is composed of two semi-annular strips (71) and each strip (71) has an annular groove (72), an inner side (not numbered), an outer side and two distal ends (not numbered). The annular groove (72) is U-shaped and defined in the inner side of the strip (71) to receive the clamping rim (66) of the bladder (60) and the clamping edge (54) of the base (50) simultaneously to combine the bladder (60) and the base (50) together. Each distal end has an ear (74) formed on the outer side and a threaded hole (742) defined in one of the distal ends of each strip (71), and a securing hole (744) defined in the other distal end of the strip. (71). When the two semi-annular strips (71) are looped around the base (50) and the bladder (60), each distal end of one strip (71) abuts the corresponding distal end of the other strip (71) to make the threaded hole (742) align with the securing hole (744). Hereafter, a bolt (76) penetrates the securing hole (744) and engages with the threaded hole (742) to secure the base (50) and the bladder (60).
According to the above description, the conventional air cushion is composed of multiple elements such as the base (50), the bladder (60) and the securing frame (70). A mold has to be prepared for each element and those elements are produced individually by different manufacturing procedures. Therefore, the conventional air cushion for exercise has high manufacturing cost and needs too many processes for combining the elements to make the air cushion.
The present invention has arisen to mitigate or obviate the disadvantages of the conventional air cushion for exercise.